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TILE-MAKING (Pottery, for artists)
CHAPTER VHI TILE-MAKING "VI thousand and fourscore of pavynge tiles delivered at Hampton Court, for to pave the Kinges new hall at XXVJs. VlUd. the thousand." Sixteenth century memorandum. TILES may be made of various kinds and sizes, but in every case they show an inclination to buckle in drying and firing. The larger the tile the stronger is this tendency to warp. The clay must not be so rich as that which is used for throwing and should be tempered to counteract the tendency to curl. A tile box as shown in Fig. 39, or a variant of it, will be required for pressing tiles by hand ; for plain tiles f " deep, for others l" deep, the size being calcu- lated to allow for shrinking. The sides hinge and the thumb screws keep it steady on the bench during work. For rough tiles, two strips nailed to the table will serve, the clay being rolled out between and cut in lengths as required. For plain tiles the wedged and tempered clay is batted out into a slab a full f " thick. The mould is dusted with French chalk, flint, or very finely 80 81 HINGE \ PIN THCJMB MOVABLE 3AK UP. RULE CATCH FIG. 39 sifted clay dust, to prevent sticking, and into it is pressed a piece cut to fit easily in the tile box, from the slab. This is firmly pressed into the box, con- siderable pressure being used. The surplus is scraped off and the top trued with an iron straight-edge. The knife can be run round the sides, then with the frame reversed a smart tap on the back will release the tile. Let the tiles toughen and then pile in stacks with flat pieces of clay or old tile between each corner and a true biscuit tile at bottom and the top. They can be piled one on the other with sand between or stacked like bricks with alternate holes for the 82 air to circulate. This retards the drying, but in any case they must be dried slowly. With plain glazed tiles a little coarse dust sprinkled over the surface before the tile is removed from the box, and well pressed in, will give a slight interest to the sur- face and take away any mechanical look. If re- quired for painting, the clay must be very finely sieved and the surface will need careful finishing by hand when dry. With coarse clay, a fine surface can be imparted with a flexible broad palette knife. For raised outline tiles a frame 1}" deep is re- quired. This allows a plaster bat f " thick to be placed at the bottom. The best way, perhaps, is to oil the frame and cast the bat in it, removing it when set and sandpapering the upper surface flat and true. The design for the tile drawn the exact size on paper is now traced on this surface. It is far better to sketch it directly onto the slab, but this demands some proficiency if the surface is to be preserved. The design is then incised with a firm sharp point, clay squeezes being taken from time to time to show the progress of the work. The plaster should be wetted to insure easy working. At the finish the design should stand out in a fairly strong and deep line square not round or angular in section. (Fig. 40.) A chisel-pointed hard pencil will be found best for finishing. This gives a clear-cut line, not too round. The bat, 83 / GLAZE PL /_ V A-POINTFOK-rarroqTLINE OEOK FINAL INCl/ED LINE Ot INCOUECT J> FIG. 40 sponged clean and porous, is then placed in the frame and the tile pressed as before. Raised outline tiles can be even more satisfactorily made by means of outlining slip squeezed from a tube or tracer in the same manner that inscriptions are made on sugared cakes, but this requires much practice to obtain good results. When glazing, the coloured glazes are applied to the different compartments with a brush. As the glaze fuses to about one third of its bulk when dry, it should be applied very liberally. It will be found that large or elaborate designs are to be avoided, as in this process they tend to 84 NOZZLE5 SLIPTRACEBS Fio. 41 become mechanical and look thin. The old Spanish and Moorish tiles in this style with jewel-like bits of colour are excellent guides and might be studied with advantage. The process of making encaustic tiles is a little more complicated. Within the frame is placed a well-lathered or soaped plaster bat (or tile) high enough to allow only a thin layer of clay \" thick being run out on top. On this when firm the design is traced or pounced. Then with a thin sharp blade it is cut down vertically to the plaster bat, and the clay removed until the whole design shows in white plaster beneath (see illustration 42). The face of the clay left must be preserved carefully, as it forms the surface of the subsequent press. The bat with clay is now placed on the bottom of the frame to allow a cast f " thick to be made. The plaster and the sides of the frame are slightly oiled 85 HINGE CLAY LAtfEn CUT OUT ON BAT % BM FIG. 42 and the plaster mixed and poured in. A soft hair brush will be useful to dislodge the air bubbles that are certain to hide in some of the many odd corners. When nearly set, the surface of the plaster can be scraped flat, and when set taken out of the frame and detached. The clay is picked out and the whole surface of the design cleaned and trimmed so that it will not hold or bind in pressing. This in turn is placed in the frame and a careful press taken. The result is a sunk design into which a different coloured clay is pressed, the tile being first allowed to toughen. The surface is lightly scraped flat and the tile slowly dried. When hard, the face is scraped again with a steel straight-edge, sandpapered, and dusted, when the design appears in two colours. (Fig. 43.) The most effective clays are fairly siliceous reds, 86 OEF E^a or TILE IN FRAME VtCTION ON AB FIG. 43 buffs, browns, and greys. When tempered with flint or quartz sand to a uniform degree, they offer a splendid opportunity for counterchange pattern. If a soft clay that contracts considerably is inlaid in a refractory clay, cracks will appear round the edges of the inlay. Thus it is found best to have the body of the tile made of the clay that contracts most. Where only a single tile is required a more direct method is possible. The tile is pressed and allowed to toughen slightly, the design being transferred as before. It is then cut round with a sharp knife 87 and the waste removed with a wire tool. A certain facility of handling is required, for great care must be taken to preserve the edges and angles. This method is, however, productive of much fresh and vigorous work. Encaustic tiles must necessarily be simple and bold in character, for anything complicated invites con- fusion; the best possible guides are the encaustic tiles of mediaeval times, especially the simple and spirited English and German Gothic. The most satisfactory way to make modelled tiles or panels is to run out upon a stout board, cross battened to prevent warping, a flat slab of clay of the required thickness. Sketch in the design with a point and model straight away onto the clay. Care must be taken, if the panel is to be fired, to see that all the added work adheres firmly to the back- ground. Where several presses are to be made, the edges of the modelled slab should be carefully trimmed with a bevel, the board oiled, and the mould made directly after the modelling is finished. The mould may be worked on in moderation. Letter- ing is much more easily incised in the mould than raised in the clay. For tiles needing much sharp- ness of detail almost the whole can be carved in the plaster. Unless done with great sympathy, however, this leads to a certain harshness and angu- larity that should be foreign to clay. Where a 88 moulded frame for a panel is required, a strickle, or profile, is cut in zinc. For short use one made from a thin slab of plaster will serve. The strickle is keyed to a straight-edge and dragged over the clay until the correct moulding emerges. This is then cut into lengths and very carefully dried. The tendency of all transparent glassy glazes to pool in hollows and run off at high points must be borne in mind. With thick matt glazes any deli- cacy of detail is apt to be lost labour. These prob- lems should be faced before the design is made, as in this process there is a certain quality of surface required by the glaze. On the other hand, in en- deavouring to make a good surface for the glaze to enhance, it is easy to slip into the over-round and slimy treatment that characterizes so much modelled pottery. Categoría:Pottery, for artists, craftsmen & teachers